Question

a ball is dropped from a height. it takes 0.2sec to cross last 6m before hitting the ground. then the height from which it was dropped (g=9.8)

Answer 1

Ahoy matey.
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Dropped, which means the ball will have the initial velocity 0m/s

We will find the velocity of ball when it reaches that point.

S = ut + 1/2 at²
6 = u × 0.2 + 1/2 × 9.8 × 0.2²
6 = 0.2u + 0.2
6 = 0.2 ( u + 1)
60/2 = u + 1
30 = u + 1
u = 29.02 m/s

Now,

v² = u² + 2as
29² = 2 × 9.8 × h
h =( 29 × 29)/ 2 × 9.8
h = 42.05m

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Gud life..